The invention is directed to the manufacture of heat bonded glass fiber insulation boards and, in particular, to low cost, high performance glass fiber insulation boards well suited for use in vacuum panels.
One of the most effective types of thermal insulation structures is a vacuum panel. However, one of the problems associated with vacuum panels, especially flat or substantially flat vacuum panels, is the need to provide support for the major surfaces of the vacuum panels, which are subjected to a compressive loading of up to one atmosphere, without greatly increasing the thermal conductivity of the vacuum panel. Most mechanical supports within a vacuum panel will greatly increase the thermal conductivity of the vacuum panel. However, as discussed in an article by H. M. Strong et al, entitled "Flat Panel Vacuum Thermal Insulation", contained in the Journal Of Applied Physics, vol. 31, #1, January 1960; a pad "of glass fibers oriented randomly in planes parallel to the pad (perpendicular to the temperature gradient)" can be used to support the walls of an insulation structure while maintaining a suitably low thermal conductivity through the proper geometric distribution of the support material. On page 46 of the Strong et al article, the formation of a glass mat by compressing the glass fiber to nearly its ultimate density and heating the glass fiber above the strain point of the glass is discussed.
While disclosing an evacuated flat-panel thermal insulation which uses a glass mat or pad with the glass fibers oriented to provide low thermal conductivity, the Strong et al article does not disclose a method of forming thin mats of glass fibers with the glass fibers in the proper geometric orientation to provide the mats with low thermal conductivities or a method of forming thick blankets of glass fibers with the glass fibers in the proper geometric orientation so that the thick glass fiber blankets can be formed into heat bonded glass fiber insulation panels having low thermal conductivities.
U.S. Pat. No. 5,330,816, issued Jul. 19, 1994, and entitled "High R Super Insulation Panel" discloses an insulation panel comprising an insulation board of heat bonded glass fibers encapsulated within a gas-tight envelope. While the patent discusses forming the glass fibers of the insulation board by a rotary process, the '816 patent does not disclose how the glass fibers are collected to form the glass fiber board or the fiber orientation of the glass fibers in the insulation board.